1. Field of the Invention
The present invention relates to a parallel robot wherein an end effector is supported by the base of the robot through plural arm assemblies which are arranged in parallel relationship with each other.
2. Discussion of the Prior Art
A parallel robot having a six-degree-of-freedom is disclosed in the Transactions of the Japan Society of Mechanical Engineers, Series C, Vol. 56, No. 523, March 1990. The disclosed parallel robot has six arms each of which is comprised of three links. The three links are connected in series through two joints. The one end of each arm is connected to a base through a joint. Each of these joints is composed of two members constituting a turning pair for rotation about a single axis. Further, the other end of each arm is connected to a bracket through joint means such as a ball joint. Driving motors are disposed on the base to swing the links adjacent to the base. With this configuration, the position and posture of the bracket is controlled.
Such conventional parallel robot has problems as follows. When the parallel robot carries out a movement of six-degree-of-freedom, the links are gradually deformed due to bending moments acting on them, whereby plays are produced. As a result, accuracy of positioning of the bracket of the parallel robot tends to be lowered. Further, because each arm is composed of three links, the entire weight of the parallel robot is relatively heavy, whereby the moving speed of the parallel robot being slow.